The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Industrial units, particularly those in the chemical, nuclear, power and petrochemical industries, employ hundreds of miles of tubing/piping. In all these applications the tubing/piping is often exposed to corrosive environments and, consequently, industries are interested in assessing the integrity of these tubes periodically. Tubing, for example, is critically important in nuclear power plants, where steam generator tubes are used to transfer thermal energy and to isolate a radioactive region from the rest of the facility. Each nuclear power plant can have 2-4 steam generators with over 3000 tubes in each generator. These tubes are continuously exposed to high temperature and pressure resulting in various types of degradation including mechanical wear, stress corrosion cracking, pitting, wall thinning, denting and inter granular attack. Concern for the operational safety of the power plants, requires periodic inspection of steam generator tubes.
Steam generator tube inspection techniques using eddy current probes have evolved over the years in an attempt to improve the speed and reliability of inspection. Eddy current inspection probes, such as bobbin coil probes, rotating probe (Rotating Pancake Coils and Plus-Point), and array probes (X-Probe, Smart Array Probe and Intelligent Probe), have been used widely for detecting and characterizing flaws in the tube wall. Bobbin coil probes offer high operational speed, but are unable to detect circumferential cracks. Rotating probes can provide a C-Scan image of tube wall and can offer a superior ability to characterize and size both axial and circumferential defects. However, the helical scanning process is slow and prone to probe wear, and the mechanical control system for probe rotation is complex and susceptible to failure. Array probes provide high inspection speed, but they need sophisticated excitation and post-processing schemes.
There is a need for a fast, robust, highly-efficient tube inspection probe.